Crown gall tumor tissue has a stable transformed phenotype; induced by transient exposure of plant tissue to living Agrobacterium tumefaciens in a wound site. The molecular basis of both the bacterial- plant interaction and the transformed phenotype will be investigated. We will try to determine whether tumors are altered by an epigenetic or genetic mechanism. Foreign DNA from an Agrobacterium plasmid will be sought in the tumor cell by DNA hybridization techniques. We will examine tumor clones for revertibility to normal phenotype. The molecular basis of bacterial virulence centers on the role of a bacterial plasmid DNA. We will determine what fraction of the plasmid DNA is essential to virulence, and will attempt to discover how the plasmid influences virulence, directly (by acting as the tumor-inducing principle), or indirectly (by influencing bacterial physiology). We will look for a crown gall virus, possibly coded for by plasmid DNA. We will characterize the susceptible phase of the plant cell cycle and study the effect of wound juice hormones on plant cell transformation. We will compare various kinds of transformed plant tissue with each other and with normal callus tissue. Grafting, growth rate, octopine/nopaline production, isozyme pattern and messenger RNA transcription and processing will be examined. The study will define the tumorous phenotype generally vs the crown gall phenotype. It will demonstra whether the transformed phenotype results from altered transcriptional patterns or post-transcriptional changes in tumor cells.